compressor dropped pkt

Hello all,

I am using the hsfmodem-7.18.00full_k2.6.8.1_12mdk-1mdk.rpm with Mandrake 10.1 
on my Dell Inspiron 2650. I getting kernel error messages about dropped 
packets. 
I am able to connect OK. I have tested with two other modems, a Motorola 
serial modem, and an Intel chipset EP536 softmodem. I can connect to either 
at a variety of speeds, but then get almost no data throughput.
Here is a typical sample from /var/log/syslog:

...
Dec 24 10:51:40 tuxtop pppd[7769]: Using interface ppp0
Dec 24 10:51:40 tuxtop pppd[7769]: Connect: ppp0 <--> /dev/ttySHSF0
Dec 24 10:51:47 tuxtop pppd[7769]: Remote message: Login ok
Dec 24 10:51:47 tuxtop pppd[7769]: PAP authentication succeeded
Dec 24 10:51:47 tuxtop pppd[7769]: Received bad configure-ack:  1a 04 78 00 18
04 78 00 15 03 2f
Dec 24 10:51:48 tuxtop pppd[7769]: local  IP address 192.168.2.31
Dec 24 10:51:48 tuxtop pppd[7769]: remote IP address 192.168.2.30
Dec 24 10:51:50 tuxtop pppd[7769]: Received bad configure-ack:  1a 04 78 00 18
04 78 00 15 03 2f
Dec 24 10:52:08 tuxtop last message repeated 6 times
Dec 24 10:52:10 tuxtop kernel: ppp: compressor dropped pkt
Dec 24 10:52:11 tuxtop kernel: ppp: compressor dropped pkt
Dec 24 10:52:12 tuxtop pppd[7769]: Received bad configure-ack:  1a 04 78 00 18
04 78 00 15 03 2f
Dec 24 10:52:13 tuxtop kernel: ppp: compressor dropped pkt
Dec 24 10:52:14 tuxtop kernel: ppp: compressor dropped pkt
Dec 24 10:52:15 tuxtop pppd[7769]: Received bad configure-ack:  1a 04 78 00 18
04 78 00 15 03 2f
Dec 24 10:52:16 tuxtop kernel: ppp: compressor dropped pkt
Dec 24 10:52:17 tuxtop pppd[7769]: CCP: timeout sending Config-Requests
Dec 24 10:52:17 tuxtop kernel: ppp: compressor dropped pkt
Dec 24 10:53:08 tuxtop last message repeated 2 times
...

Any suggestions?

Best regards,

Ross